1. Field of the Invention
The present invention relates to a semiconductor device fabrication, and more particularly to a method for forming a photosensitive device with color filter.
2. Description of the Related Art
FIG. 1 are schematic representations of structures in the final stages of formation of a photosensitive device using conventional technology. Referring to FIG. 1A, a planarized inter-metal dielectric layer 100 with a photoreceiving region 130 therein is formed on a substrate (not shown). A metal layer 114 is deposited and defined to expose the photoreceiving region 130 on the inter-metal dielectric layer 100, and a protective layer 150 is formed thereon.
Referring to FIG. 1B, a thick planar film 152, for example spin-on glass, is coated on a protective layer 150 for planarization. The planar film 152 and protective layer 150 are transparent for enhancing light sensitivity of the photosensitive device. A color filter process, comprising coating R, G, and B filters, development, etching and top coating, is then performed to form color filter 112. Next, another protective layer 120 is coated thereon to cover the color filter 112 and planar film 152.
The coated planar film 152 described cannot effectively fill in some concave areas of the photosensitive device to produce a flat surface over the entire wafer surface. Additionally, the planar film 152 must achieve a thick thickness, about 2 μm, to produce a flat surface. Shrinkage, however, may be generated, affecting flatness of the surface of the planar layer 152. The uneven layer 152 under the color filter 112 may diminish color performance of the device. Due to the unevenly coated dielectric layer 152, a yellow strip may occur in the step height regions, for example the regions near the bonding pads or the scribe lines.